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Calcium scoring to guide aspirin use

Calcium scoring could help guide the treatment of coronary heart disease (CHD), by avoiding the unnecessary use of preventive medications, according to a report published recently in Circulation: Cardiovascular Quality and Outcomes.1

To estimate the potential of coronary artery calcium (CAC) scoring to guide aspirin use for primary prevention of CHD, the authors studied 4,229 participants from MESA (Multi-Ethnic Study of Atherosclerosis) who were not on aspirin at baseline and were free of diabetes mellitus.

Using data from median 7.6-year follow-up, 5-year number-needed-to-treat estimations were calculated by applying an 18% relative CHD reduction to the observed event rates. This was contrasted to 5-year number-needed-to-harm estimations based on the risk of major bleeding reported in an aspirin meta-analysis. Results were stratified by a 10% 10-year CHD Framingham Risk Score (FRS).

Dr Michael Miedema (Minneapolis Heart Institute, Minneapolis, USA)

Individuals with CAC ≥100 had an estimated net benefit with aspirin regardless of their traditional risk status (estimated 5-year number needed to treat of 173 for individuals <10% FRS and 92 for individuals ≥10% FRS, estimated 5-year number needed to harm of 442 for a major bleed).

Conversely, individuals with zero CAC had unfavorable estimations (estimated 5-year number needed to treat of 2036 for individuals <10% FRS and 808 for individuals ≥10% FRS, estimated 5-year number needed to harm of 442 for a major bleed). Sex-specific and age-stratified analyses showed similar results.

Speaking to BJC Arrhythmia Watch, author Dr Michael Miedema (Minneapolis Heart Institute, Minneapolis, USA) said: “The purpose of our study was to look at the potential for calcium scoring to change management, specifically could it help guide aspirin therapy. There are multiple screening tests available for cardiovascular prevention but in order to have any value, a test has to lead to a change in clinical decision making or patient behaviour if it is to be of any value.”

“Our findings do not confirm that calcium scoring should be recommended for all individuals but rather our findings add to the growing evidence that calcium scoring could help guide use of preventive medications as there is similar data for calcium scoring guiding statin therapy. Everyone should eat a healthy diet, exercise, and not smoke – you don’t need a screening test to decide if a person should follow those lifestyle behaviors,” Dr Miedema continued.

Dr Miedema added: “However, I do not believe that everyone should start preventive medications because of their age. With the new USA cholesterol guidelines taking an absolute risk based approach (which heavily relies on age), I think we will see more and more data to support calcium scoring as a way to potentially avoid using aspirin and statin medications. If you don’t have any plaque in your arteries, it is very unlikely that you are going to have a heart attack, so in those individuals the risks and costs of the preventive medications likely outweigh the very small benefit”.

“Calcium scoring is not a new technology and the current charge at most healthcare facilities in the US is approximately $100 per scan. The current radiation dose is less than a millisievert (which is less than a mammogram). We desperately need a randomised trial to evaluate the true benefit of calcium scoring but there currently isn’t one ongoing (or starting soon as far as I know). Therefore, we will have to rely on the observation data that we do have to determine its potential benefit,” Dr Miedema concluded.